Trophic Relations of Brown and Black Bears in Several Western North American Ecosystems

摘要: We examined the historical and current diets of brown bears (Ursus arctos) black (U. americanus) in Greater Yellowstone Ecosystem, Glacier National Park immediately adjacent areas national forests, Cabinet-Yaak mountains northwestern Montana northern Idaho, Blackfeet Flathead Indian reservations east south Park, Kenai Peninsula Alaska, southwestern states Colorado, New Mexico, Arizona. Dietary estimates are an essential first step understanding variation productivity density populations and, therefore, predicting success reintroduced populations. Hair or bone samples from 14 federal state agencies, museums, universities were via stable isotope analyses to quantify importance animal plant resources sympatric bears. Stable have numerous advantages over fecal direct observation because (1) individuals thereby specific age sex classes within a population can be compared, (2) long-dead compared living evaluate changes ecosystems. Meat content bear diets, which varied extensively between all populations, averaged 51 ± 19% (x SD) for subadult adult males females Ecosystem 11 14% mountains. Within these ecosystems, male more carnivorous than any other class. Brown that used easily obtained, abundant meat sources had dietary contents generally ≥70%. The meat:plant ratios (1,000 YBP) (1908-18) similar diets. Sympatric Wyoming, Montana, Idaho ecosystems not different classes, except males. Alaskan made extensive use salmon (Oncorhynchus spp.) when rare (53 28% diet), but did with